I am trying to access data for historical orders through jForex API using function

com.dukascopy.api.IHistory.readOrdersHistory(Instrument instrument, long from, long to, LoadingOrdersListener ordersListener, LoadingProgressListener loadingProgress) ;

In the console everything looks proper, I can see messages that the client is connecting and that request for orders is generated. I can see messages 'Downloading data...' and 'All orders loaded', which should be the correct behavior, but the problem is that the code inside the Listeners for this function does not execute, so in fact I do not have access to this data. I have set DEBUG mode in log4j for the client and I can see that data for orders is received correctly in the log file. I see message

RECEIVE : {"mergedPositions":[],"groups" ....

but immediately after this there is line saying

ERROR ( ?:?) -
java.lang.NullPointerException
at com.dukascopy.charts.data.a.a.a(Unknown Source)
at com.dukascopy.charts.data.datacache.aq.run(Unknown Source)

My guess is that here is the problem, after getting the orders from the server there is NPE and listeners are not invoked. Also it is impossible to do any code level debugging because there is not source for jForex client, is obfuscated and compiled without lines information, so I cannot guess what could be the problem. Could you please help me with this problem, or how to approach in debugging this kind of problems taking into account jForex documentation and source accessibility.

Thanks,
-D.